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Math Help - Logarithms

  1. #1
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    Logarithms

    How do you do

    Log base 5 of (x ^2 + x + 4) = 2?
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  2. #2
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    Quote Originally Posted by Alan306090 View Post
    How do you do

    Log base 5 of (x ^2 + x + 4) = 2?
    first, change it to an exponential equation ... you'll get a quadratic to solve.

    don't forget to check your solutions in the original log equation for domain issues.
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  3. #3
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    Quote Originally Posted by skeeter View Post
    first, change it to an exponential equation ... you'll get a quadratic to solve.

    don't forget to check your solutions in the original log equation for domain issues.
    25 = x ^2 + x + 4

    0 = x^2 +x -21

    then what? I can't factor it
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  4. #4
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    Quote Originally Posted by Alan306090 View Post
    25 = x ^2 + x + 4

    0 = x^2 +x -21

    then what? I can't factor it
    x = \frac{-b\pm\sqrt{1^2-4\times 1\times -21}}{2\times 1}=\dots
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